Pneumonia

Pneumonia (nu-MO-nyah) is an inflammation of the lungs, usually caused
by infection, that can result in breathing difficulty.

KEYWORDS

for searching the Internet and other reference sources

Atypical pneumonia

Mycoplasma pneumonia

Pneumococcal vaccine

Pneumococcus

Streptococcal pneumonia

Walking pneumonia

What Is Pneumonia?

When a person breathes, air enters the lungs and travels through millions
of tiny sacs. These sacs, known as alveoli (al-VEE-o-lye), are where
oxygen is transferred to the blood, which carries it to all parts of the
body. When someone has pneumonia, the lung tissue becomes inflamed and the
alveoli fill with mucus
*
and other debris, making it difficult for oxygen to be transferred. When
normal amounts of oxygen cannot reach the body's cells, many
symptoms may develop.

Bacteria or viruses usually cause pneumonia. In some cases, a virus may
directly cause the disease. Also, viral infections that lead to
respiratory symptoms (such as those of a common cold) often produce
inflammation and mucus buildup that makes it easier for bacteria to take
hold and infect the lungs. Fungi or parasites are less common causes of
pneumonia. Chemicals, drugs, or radiation also can cause lung
inflammation. Aspiration (as-puh-RAY-shun) pneumonia occurs when someone
accidentally inhales food or vomited material into the lungs.

*
mucus
(MYOO-kus) is a thick, slippery substance that lines the insides of
many body parts.

*
strains
are various subtypes of organisms, such as viruses or bacteria.

Pneumonia is a common infection among people who are hospitalized for
something else. Such hospital-acquired infections are especially
widespread among people recovering from surgery and those who are placed
on breathing machines (ventilators). Hospital-acquired pneumonia is almost
always bacterial and is often caused by strains
*
of bacteria that are resistant to many antibiotics. For this reason, and
because it affects people who are already sick, hospital-acquired
pneumonia is more frequently serious or fatal compared to cases of
pneumonia acquired outside the hospital.

What Are Some Different Types of Pneumonia?

Bacterial pneumonia

Bacterial pneumonia can attack anyone, from infants to adults, and it is
most frequently fatal among the elderly. The most common cause of
bacterial pneumonia is
Streptococcus pneumoniae
(strep-tuh-KAH-kus nu-MO-nye), also called pneumococcus (nu-moh-KAH-kus).
If the infection is not properly treated with antibiotics, the bacteria
can multiply and cause infection not only in the lungs but also in the
bloodstream, brain, and other parts of the body. Other bacterial causes
include:

Mycoplasma pneumoniae
(my-ko-PLAZ-muh nu-MO-nye), which leads to an infection known as
"walking pneumonia" because it is often mild enough to go
undiagnosed for a long period of time

Staphylococcus
(stah-fih-lo-KAH-kus), which usually affects patients in hospitals

Chlamydia trachomatis
(kla-MIH-dee-uh truh-KO-mah-tis), often seen in infants; two other
species of chlamydia also can cause pneumonia, usually in adults:
Chlamydia pneumoniae
(kla-MIH-dee-uh nu-MO-nye) and
Chlamydia psittaci
(kla-MIH-dee-uh sih-TAH-see)

Species of the bacteria
Klebsiella
(kleb-zee-EH-luh),
Pseudomonas
(su-doh-MO-nus), and
Legionella pneumophila
(lee-juh-NEL-uh nu-MO-fee-luh, the bacterium that causes
Legionnaire's, lee-juh-NAIRS, disease)

Viral pneumonia

Viral pneumonia, usually seen in children, makes up nearly half of all
pneumonia cases. This type of pneumonia is usually not severe or long
lasting. Causes of viral pneumonia include:

respiratory syncytial (RES-puh-ruh-tor-e sin-SIH-she-ul) virus, or RSV,
which typically causes more severe illness in infants and very young
children

*
respiratory tract
includes the nose, mouth, throat, and lungs. It is the pathway through
which air and gases are transported down into the lungs and back out of
the body.

*
intestines
are the muscular tubes that food posses through during digestion after
it exits the stomach.

*
bladder
is a sac-like organ that stores urine before releasing it from the
body.

*
croup
(KROOP) is an infection involving the trachea (windpipe) and larynx
(voicebox) that typically occurs in childhood. It causes inflammation
and narrowing of the upper airway, sometimes making it difficult to
breathe. The characteristic symptom is a barking cough.

Fungal pneumonia

Fungal pneumonia usually targets people with weakened immune systems. For
instance, pneumonia caused by
Pneumocystis carinii
(nu-mo-SIS-tis kah-RIH-nee-eye), which was recently identified as a
fungus, is most common in patients with compromised
immune systems, particularly those who have AIDS
*
. Other fungal infections that can involve the lungs include
histoplasmosis (his-toh-plaz-MO-sis), blastomycosis (blas-toh-my-KO-sis),
coccidioidomycosis (kok-sih-dee-oyd-o-my-KO-sis), and aspergillosis
(as-per-jih-LO-sis).

How Common Is Pneumonia?

Pneumonia was a leading cause of death in the United States in the early
decades of the twentieth century. With the help of antibiotics, it dropped
to number five by 2000. Although that is certainly an improvement, the
disease is still common enough to affect between 3 and 5 million people
each year in the United States, with more than 60,000 deaths annually.

Is Pneumonia Contagious?

The bacteria and viruses that cause pneumonia can pass from person to
person. When people who are infected sneeze, cough, laugh, or talk, they
expel bacteria or viruses into the air in tiny drops of moisture that can
be breathed in by others. The germs also can contaminate surfaces that an
infected person touches, such as doorknobs, desks, and keyboards. If
people do not wash their hands after touching these things, they could
become infected by casually touching their eyes, mouth, or nose. An
infection contracted this way can lead to pneumonia, although it usually
does not.

*
AIDS
, or acquired immunodeficiency syndrome (ih-myoo-no-dih-FIH-shen-see),
is an infection that severely weakens the immune system: it is caused by
the human immunodeficiency virus (HIV).

William Osler, 1849-1919

Sir William Osler, often called the father of modern medicine, spent
much of his life studying pulmonary diseases (diseases of the lungs) and
is known for dubbing pneumonia the "old man's
friend." Ironically, Osler himself died of pneumonia after
contracting influenza.

How Do People Know They Have Pneumonia?

Depending on the cause of the pneumonia and the health of the person with
the infection, its symptoms can vary. Symptoms of bacterial pneumonia may
appear suddenly and include high fever, chills, rapid breathing, a deep
cough that brings up greenish mucus that is sometimes mixed with blood,
and severe chest pain that worsens with breathing and coughing. A
persistent dry cough, sore throat, and skin rash mark mycoplasma pneumonia
(walking pneumonia).

Viral pneumonia can produce symptoms similar to those of the flu,
including fever, muscle aches, breathlessness, rapid breathing, and a dry
cough, which can worsen and eventually bring up a small amount of mucus.

Other symptoms that may accompany both bacterial and viral pneumonia
include loss of appetite, nausea (NAW-zee-uh), vomiting, headache, and
excessive sweating. In people with weakened immune systems, pneumonia can
quickly become worse.

How Do Doctors Diagnose and Treat Pneumonia?

Diagnosis

To identify the infection, the doctor first takes a history of the
patient's symptoms and then will listen to a patient's chest
with a stethoscope. Fluid in the lungs often produces a crackling sound
when a person breathes, which can point to pneumonia. Sometimes the doctor
will not be able to hear any air moving through the affected part of the
lung. Chest X rays also may be taken, and a cloudy, dense-appearing area
may be seen in one or both lungs, particularly in a person who has
bacterial pneumonia.

Next, the doctor may take samples of blood and sputum (SPYOO-tum,
coughed-up mucus) to try to find out what is causing the pneumonia. These
samples can be examined under a microscope and sent to the lab for culture
*
and identification of the organism causing the infection. In severe
cases, a bronchoscopy
*
or a lung biopsy
*
may be performed.

*
culture
(KUL-chur) is a test in which a sample of fluid or tissue from the body
is placed in a dish containing material that supports the growth of
certain organisms. Typically, within days the organisms will grow and
can be identified.

*
bronchoscopy
(brong-KOS-kopee) is a procedure used to examine the bronchi, the major
air passages in the lungs, with an instrument called a bronchoscope,
which is a tool for looking inside the lungs that is made up of a
lighted tube with viewing lenses.

*
biopsy
(BI-op-see) is a test in which a small sample of skin or other body
tissue is removed and examined for signs of disease.

*
dehydration
(dee-hi-DRAY-shun) is a condition in which the body is depleted of
water, usually caused by excessive and unreplaced loss of body fluids,
such as through sweating, vomiting, or diarrhea.

Treatment

Antibiotics are used to treat bacterial pneumonia. Antiviral or antifungal
medicines are prescribed in some cases of viral or fungal illness. In
severe cases, patients may need to be hospitalized, particularly if they
are in danger of dehydration
*
, need more oxygen, or cannot breathe well enough on their own.

People with pneumonia get relief from symptoms and aid their recovery by:

taking an over-the-counter, non-aspirin pain reliever such as
acetaminophen (uh-see-teh-MIH-noh-fen) to ease fever and muscle aches

resting and drinking liquids to combat dehydration

using a humidifier to keep air cool and moist, making it easier to
breathe

staying away from cigarette smoke, which irritates the lungs

With treatment, bacterial pneumonia symptoms usually improve within a day
or two and are gone in 1 to 2 weeks, but symptoms of viral pneumonia and
mycoplasma pneumonia can last longer.

Medical complications

In severe cases, respiratory failure (the inability to breathe adequately)
can occur, requiring the person to be hospitalized and placed on a
ventilator for breathing assistance. Pus
*
can collect in the spaces surrounding the lungs and may need to be
drained surgically. The lungs also can become scarred, leading to
long-term breathing problems. These complications, particularly when they
affect elderly people or patients with other health problems, can
ultimately lead to death.

How Can Pneumonia Be Prevented?

The pneumococcal (nu-moh-KAH-kal) vaccine
*
works well against pneumococcal bacteria that cause pneumonia and is
recommended for people over age 65 and children under age 2 years, those
with certain other illnesses, or those with weakened immune systems. The
vaccine typically needs to be given only once in a lifetime. Yearly flu
vaccines can help prevent pneumonia caused by influenza viruses. Because
pneumonia often is caused by contagious respiratory infections, people can
protect themselves further by avoiding being near people who are sick,
hand washing, not touching used tissues, and never sharing food, drinks,
or eating utensils.

*
pus
is a thick, creamy fluid, usually yellow or greenish in color, that
forms at the site of an infection. Pus contains infection-fighting white
cells and other substances.

*
vaccine
(VAK-seen) is a preparation of killed or weakened germs, or a part of a
germ or product it produces, given to prevent or lessen the severity of
the disease that can result if a person is exposed to the germ itself.
Use of vaccines for this purpose is called immunization.

Resources

Organizations

The American Lung Association, 61 Broadway, 6th Floor, New York, NY
10006. The American Lung Association offers information about pneumonia
on its website.
Telephone 212-315-8700
http://www.lungusa.org

U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton
Road, Atlanta, GA 30333. The CDC is the U.S. government
authority for information about infectious and other diseases. It
provides information about pneumonia at its website.
Telephone 800-311-3435
http://www.cdc.gov

Website

KidsHealth.org
. KidsHealth is a website created by the medical experts of the Nemours
Foundation and is devoted to issues of children's health. It
contains articles on a variety of health topics, including pneumonia.
http://www.KidsHealth.org